Obtusion and Assisted Hatching: No Negative Effect on Pregnancy Success Rates in IVF

Objective: To evaluate the impact of obtusion and assisted hatching on positive pregnancy outcomes following in vitro fertilization (IVF) at a single reproductive medicine center. Design: Retrospective cohort study. Materials and Methods: Data from 750 IVF cycles conducted at a single reproductive medicine center between January 2018 and December 2023 were retrospectively analyzed. The primary outcome was clinical pregnancy, defined by the presence of a gestational sac on ultrasound at 6–7 weeks of gestation. Independent variables included maternal age, blastocyst stage (2–4), inner cell mass (ICM) quality, trophectoderm (TE) quality, and the presence of obtusion. Statistical analyses were performed using binary logistic regression to determine the odds ratios (OR) and 95% confidence intervals (CI) for factors associated with positive pregnancy outcomes. Post hoc analyses were conducted to validate significant findings. Results: A total of 750 IVF cycles were included. Neither obtusion nor assisted hatching significantly affected pregnancy rates. Key findings included: • Obtusion Impact: OR 0.95, 95% CI 0.42–2.18, p = 0.910 • Assisted Hatching (Blastocyst Stage 2–4): Pregnancy rates varied but were not statistically significant (e.g., Stage 2: 80.0%, p = 0.789). • TE Quality: Higher TE quality was significantly associated with positive pregnancy outcomes (OR 2.00, 95% CI 1.50–2.67, p < 0.001). • ICM Quality: Quality A ICM was also a significant predictor of positive outcomes (OR 1.95, 95% CI 1.20–3.17, p < 0.01). • Maternal Age: Did not show a significant impact on pregnancy outcomes (OR 0.98, 95% CI 0.94–1.02, p = 0.294). Conclusions: The presence of obtusion and assisted hatching (embryo stages 2–4) does not negatively impact positive pregnancy outcomes following IVF. The quality of trophectoderm and inner cell mass are significant predictors of positive pregnancy outcomes. These findings support the continued use of these techniques in clinical practice without adverse effects on pregnancy rates and underscore the importance of embryo quality in predicting IVF success.